A developing device has a flow passage forming member extending in a rotation direction of a development sleeve of a toner delivering mechanism between the development sleeve and an inner wall of a main body of the developing device. In addition, an inlet of an intake flow passage portion provided between the flow passage forming member and the development sleeve and an outlet of a discharge flow passage portion provided between the flow passage forming member and the inner wall of the main body of the developing device are adjacent to each other. Consequently, an air pressure increase inside the developing device body is suppressed, and toner scattering out of the main body of the developing device is suppressed.